BACKGROUND AND OBJECTIVES: Craniofacial abnormalities present in Klippel-Feil Syndrome (KFS) and Down Syndrome (DS) can hinder access to the airways. Oropharyngeal surgeries also require special attention with the airways. The association of both syndromes in a patient scheduled for tonsillectomy is a rare condition that imposes challenges to the anesthetic-surgical treatment. The objective of this report was to discuss the approach of the airways and the risks of cervical manipulation in a patient with KFS and DS undergoing tonsillectomy. CASE REPORT: This is a 5 years old child with diagnosis of KFS and DS and instability of the atlantoaxial joint who underwent tonsillectomy under general balanced anesthesia. Ventilation under face mask and tracheal intubation were done with the neck in the neutral position. The perfect visualization of the epiglottis and vocal cords allowed tracheal intubation with conventional laryngoscopy. The surgery was also performed without cervical extension and without intercurrences. CONCLUSIONS: Although access to the airways can be easy, anatomical changes presuppose the presence of difficult airways in patients with KFS and DS. Differentiated care and adequate resources are mandatory to avoid complications during approach of the airways. Cervical manipulation should be avoided in the presence of instability of the atlantoaxial joint due to the risk of neurological damage.